Fountain pen



Jan. 27, 1948.

..L. J. BIRO FOUNTAIN PEN 2 Sheets-Sheet 1 Filed Aug. 2, 1944 glwvc/ntomZ J 13121 0 Jan. 27, 1948. I L. J. BlRo 2,435,123

FOUNTAIN PEN Filed Aug. 2, 1944 2 Sheets-$heet 2 Patented Jan. 27, 1948UNITED STATES rem FOUNTAIN PEN Application August 2, 1944, Serial No.547,758

: Claims. (01. 120-43) This invention relates to improvements infountain-pens, and particularly to fountain-pens of the rolling-ball tiptype. The invention is shown as applied to pens of the general typeshown in my application Serial Number 491,206, filed June 17, 1943,patented December 11, 1 945, No. 2,390,636, and in application ofGerardo H. van Spankeren, Serial Number 508,977, filed November 4, 1943,patented August 6, 1946, No. 2,405,381.

While the air intake system has generally given good results due to thedevices provided for blocking the ink and preventing same from passingthrough the only communication to the atmosphere, in practice severaldrawbacks are observed which frequently afiect the operation of thewriting instrument. Since certain of said fountain pens only admit anink charge of less than one half the capacity of the reservoir, so as tokeep the air intake conduit isolated from the ink, the latter onlyreaches the feed conduit when the fountain-pen is in writing position,and since the ink is substantially dense, it takes some time to reachthe feed conduit, so that upon starting to write, with the pen inwriting position, the consumption of ink may cause the formation of anair pocket at the starting point of the feed liquid vein, before themass of ink contained in the reservoir reaches said point by-gravity,whereby said ink mass will cover said pocket, leaving an air bubble inthe capillary conduit which will interrupt the continuity of the vein.

Experiments have shown that with pens of the type shown in the VanSpankeren application. the best way of avoiding the interruption of theink vein is to provide a stagnant charge adjacent the end of the feedconduit, arranged so that the level thereof will not be affected bygravity. However, such stagnant charge should in turn be fed by the mainreservoir, and therefore the communication between the latter and thecontainer for said stagnant charge should meet certain conditions and beprovided with means capable of neutralizing the action of air, and'thisis achieved by means of the present invention.

The invention comprises an intermediate chamber between the ink.reservoir proper and the feed conduit, arranged so as to have a smallreserve of ink between the feeder and the main reservoir, which chamberis preferably provided with a cavity shaped so as to constitute a trapfor collecting any bubbles which might accidentally reach saidintermediate chamber- For this purpose, the partition dividing theintermediate chamber and the main reservoir is preferably provided withan extension towards the feed conduit, said extension being so shapedthat the orifice, which is of a substantially capillary section, will belocated at the end of the taper of said extension. Thus, thisarrangement not only provides a means for holding a certain amount ofliquid which will constitute a small reserve for preliminaryconsumption, but will also act as a funnel for the mass of ink arrivingby gravity when the fountain-pen is placed in writ ing position. Theshape of the partition also provides a cavity within said intermediatechamber, which will trap and retain any air bubbles.

Apart from the above, the invention contemplates other objects amongwhich may be men-- 'tioned the provision of means for insuring apermanent and uninterrupted feed of the ink.

A further object of the invention is to provide means whereby a changein position of the instrument will not afiect the charge adjacent thefeed conduit.

A still further object of the invention is to .provide an intermediatecontainer which will act as a reserve, the full charge of which will notbe affected by the initial consumption of Other objects and advantagesof the invention will become apparent from the course of the:following-description, when read in conjunction with the accompanyingdrawings, illustrating the invention by way of example and in apreferred embodiment.

In the drawings:

Fig. 1 is a longitudinal sectional view of the main portion of afountain-pen embodying the present invention.

'Fig. 2 is a sectional view'of the main portion "of a fountain-pen,showing the manner in which the writing tip may be detached andattached.

'Fig. 3 is a view showing the fonutaimpen in inverted position.

Fig. 4 is a graphical illustration of the change in position of the inkupon placing the instrument with the writing tip downwards.

The same reference characters have been used to indicate like orcorresponding parts or elements throughout the drawings.

As may be seen from the drawings, a is the ink reservoir of afountain-pen of the ball tip type, having an air intake constituted by aconduit 12 comprising orifices l, a channel 2, intermediate chambers 3and 4 and a tube 5 terminating at the center of the reservoir a, in sucha manner that the mouth 5' of the tube 5 will remain equidistant notonly from the ends but also from the side walls of the ink reservoir 0..Since the purpose of this arrangement of tube 5 centrally of saidreservoir is to prevent the ink from reaching said mouth 5', the tube 5is provided in the vicinity of said mouth with a deflecting member 5which will deflect the ink running along said tube, as clearly shown inFig. 4.

As stated above, the fountain-pen is of the type wherein the tip 1terminates in a ball 8 fitted Within a setting 9 to which the ink feedconduit I leads.

Since the ink should not reach the mouth of tube 5, it will be necessarythat the ink charge be less than one half the capacity of the reservoira, as shown in Figs. 1, 3 and 4. This means that the feed is onlyrestored when the pen is in writ ing position.

It will therefore be seen that while the air intake system with a tubeleading to the center of the ink reservoir has the advantage ofpreventing any leakage of ink through the air intake, still, due to thefact that the reservoir only admits a charge of ink equal to less thanone half the capacity of said reservoir, this system has the drawback ofthe separation of the ink mass relative to the feed reservoir when thepen is not in writing position.

The above mentioned drawback is overcome by means of the interpositionof an intermediate chamber 0 between the reservoir a and the feedconduit It) so as to act as a direct supply for said feeder I 0.

In order to maintain a practically permanent charge of ink in saidintermediate chamber 0, the latter is divided from the reservoir a bymeans of a. partition H having a single central orifice l2 of asubstantially capillary nature, so that once said intermediate chamberis charged with ink, the latter will be prevented from passing to themain reservoir, regardless of the position of the writing instrument.This is due to the fact that the only outlet of said intermediatechamber 0 is constituted by the passage I0 leading to the conduit I0terminaing in the setting 9for the writing ball 8, and since the ball 8forms a seal, the intermediate chamber 0 will have no air intake.

Inasmuch as the mass of ink in the reservoir a will not reach theorifice l2 when the position of the fountain-pen is inverted orhorizontal, there will be times during which the intermediate chamher 0will be the sole supplier of the ink feed. In effect, when theinstrument is placed in the position illustrated inFig. 4, due to thefact that the ink is very dense, it will take some time to rundownwardly, so that for a short while the writing ball will be suppliedwith ink by the chamber c, which will thus lose part of its charge.

completed by the sudden arrival of the mass of ink from the reservoir a,there would be danger of forming an air bubble, and therefore thepartition H cannot be an ordinary fiat diaphragm with a perforation, butshould be of a special shape, as shown in the drawings, and this featureconstitutes one of the essential parts of the present invention. 7

The shape of the partition H near the orifice l2 should be such as tomaintain by capillarity a small reserve of ink next to the border l2determining the minimum section of said orifice I2, while at the sametime it should form a funnel for the mass of ink from the reservoir a,so that the latter will contact the contents of the intermediate chambera without forming air bubbles.

This funnel-like shape is obtained by means of a central projection H ofpartition I I towards the interior of the intermediatechamber c. SaidShould the charge of the intermediate chamber 0 be projection ll ofpartition II is coaxial with the fountain-pen, and therefore the orificel2 will register with the conduit 10 and with the mouth 5 of tube 5.

Apart from acting as a funnel and storing a small reserve of ink in theenlargement adjacent the orifice [2, the central projection II alsoprovides a trap l3 between said projection and the walls of chamber 0.Should an air bubble accidentally reach or be formed in the intermediatechamber 0, it would be trapped by trap i3 and remain out of the feedpath, as shown in Fig. 4.

The operation of the device is as follows:

The fountain-pen is first charged with dense ink by filling'theintermediate chamber 0 to the full capacity thereof, while the mainreservoir a is charged with an amount of ink equal to less than thecapacity thereof, as mentioned above, so that the ink will not reach themouth 5' of tube 5, regardless of the position of the pen.

When the fountain-pen is placed in writing position with the ball tipdownwardssas shown in Fig. 4, the dense ink will slowly fiow downwardsand contact the ink in chamber 0 through the orifice l2, but when theposition of the fountainpen is inverted as shown in Fig. 3, the inkcharge of reservoir a will slowly flow backwards, away from the chargecontained in chamber 0.

The withdrawal of the ink in reservoir 0. will not affect the charge inchamber 0 which will remain filled up to the orifice l2. Due to thefunnel-shaped projection H, the ink will remain adhered by capillarityin the enlargement next to the border I2 of orifice l2. This smallamount of ink maintained by capillarity in the enlargement next to theborder l2 will constitute a sufficient reserve for the initialconsumption corresponding to the first traces of the pen when the latteris placed in writing position. Thus, although the charge in chamber 0 istemporarily spaced from the ink charge in the main reservoir a, thecharge in chamber 0 will not be affected by the initial consumption ofink, the length of the reservoir being so calculated that the inktherein will reach and contact the ink in chamber a 0 before the smallreserve next to the border I2 is consumed in its entirety.

Due to the funnel-like shape of partition II, the dense ink within themain reservoir a will contact the ink in chamber 0 without forming airbubbles. Any air bubbles which might be formed by shaking thefountain-pen will be trapped in trap I3.

The intermediate chamber 0 may be charged with ink either through theorifice l2 or through the feed conduit 10, for which purpose the tip 1is detachable, having a shank portion 14, as shown in Fig. 2, which isfrusto-conical and fits in a corresponding frusto-conical socket 15pro-- vided in the body of the barrel of the fountainpen. The tip I withthe shank portion l4 thereof is provided with an axial perforationconstituting the final length of the feed conduit ID leading to thesetting 9 of the writing ball 8.

It is evident that in carrying the invention into practice, severalmodifications, changes and adaptations thereof will occur to thoseskilled in the art, without departing from the scope of the invention asclearly set forth in the appended claims.

I claim:

1. Improvements in fountain-pens comprising a writing tip with a writingball arranged in a setting at the terminal end of a feed conduit the inkreservoir of which is provided with an air intake constituted by aconduit entering said reservoir by means of a tube ending in a mouthlocated at the center of said reservoir approximately equidistantly fromthe ends and side walls thereof, so as to remain out of reach of inkcontained in said reservoir, wherein an intermediate chamber is providedbetween said reservoir and said feed conduit, said intermediate chamberbeing adapted to be charged with ink to the full capacity thereof, saidintermediate chamber being separated from said reservoir by means of apartition having a central funnel-shaped projection projecting into saidintermediate chamber and terminating in an orifice constituting the onlycommunication between said intermediate chamber and said reservoir.

2. Improvements in fountain-pens comprising a removable writing tip witha writing ball arranged in a setting at the terminal end of a feedconduit the ink reservoir of which is provided with an air intakeconstituted by a conduit entering said reservoir by means of a tubeending in a mouth located at the center of said reservoir approximatelyequidistantly from the ends and side walls thereof, so as to remain outof reach of ink contained in said reservoir, wherein an intermediatechamber is provided between said reservoir and said feed conduit, saidintermediate chamber being adapted to be charged with ink to the fullcapacity thereof, said intermediate chamber being separated from saidreservoir by means of a partition having a central funnelshapedprojection projecting into said intermediat chamber and terminating inan orifice constituting the only communication between said intermediatechamber and said reservoir, said projection of said partition forming abubble trap with the side walls of said intermediate chamber.

3. Improvements in fountain-pens comprising a writing tip with a writingball arranged in a setting at the terminal end of a feed conduit the inkreservoir of which is provided with an air intake constituted by aconduit entering said reservoir by means of a tube ending in a mouthlocated at the center of said reservoir approxiforming the bottom of thereservoir of the pen mately equidistantly from the ends and side wallsthereof, so as to remain out of reach of the ink contained in saidreservoir, wherein an intermediate chamber is provided between saidreservoir and said feed conduit, said intermediate chamber being adaptedto be charged with ink to the full capacity thereof, said intermediatechamber being separated from said reservoir by means of a partitionhaving a central funnel-shaped axial projection projecting into saidintermediate chamber and terminating in an orifice coaxial with saidfeed conduit and constituting the only communication between saidintermediate chamher and said reservoir.

4. A fountain pen according to claim 1 in which the intermediatereservoir is provided with a capillary inlet in communication with theink when in a writing position and having an axially extending capillaryopening projecting into the interior of said chamber and a floor opposedto the funnel shaped portion having a feeder conduit coaxial with thecapillary opening leading to the writing tip.

LASZLO J OZSEF' BIRO.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,563,408 Sutherland Dec. 1, 1925743,430 Berg Nov. 10, 1903 1,313,056 Blackwood Aug. 12, 1919 441,111Shattuck Nov. 18, 1890 2,258,841 Biro Oct. 14, 1941

